1. Field of the Invention
This invention relates to a centrifugal blower assembly for an automotive vehicle. More particularly, the present invention relates to a centrifugal blower assembly used in a heat exchange system of an automotive vehicle and wherein the centrifugal blower includes a diffuser at its exit end.
2. Disclosure Information
In automotive heating and air conditioning systems, the air flowing through a heat exchanger core is generated by a centrifugal blower upstream of the core and connected to it by a passage or plenum. The radial flow squirrel cage type of blower, such as a centrifugal fan, is commonly used because it is efficient and compact. The blower is contained within a scroll-shaped, volute housing which ends at an exit end and is connected to the heat exchanger by a straight or angled housing. FIG. 1 shows a typical prior art centrifugal blower assembly having a housing 10 with a passage connected to a heat exchanger. The passage 12 of the FIG. 1 embodiment shows straight walls.
In known fashion, the blower wheel pulls air into the blower housing 10. The amount of air moved by the blower increases as a point on the wheel moves within the housing from an edge of the inlet opening of the housing. The housing is positioned progressively further from the wheel in the direction of rotation to accommodate the growing volume of air, that being due to the volute shape of the housing. The blower action produces a stream of high velocity air (shown by arrows) which is ejected from the exit end of the housing. The high velocity stream tends to stay together hugging the walls of the passage adjacent the edges. As the air continues to impact upon the side wall edges of the passage way, air separation occurs at 14, 16. This separation is reversed several times down the length of the passage way and results in noise and decreased efficiency of the centrifugal blower.
It is desirable that the air velocity through the passage from the blower housing to the heat exchanger be uniform and that separation of the air flow be prevented to reduce the noise produced by the blower as well as increase the efficiency of the blower. U.S. Pat. No. 4,991,646 discloses one method of minimizing airflow separation by providing a plurality of baffles within the passage to break up the high velocity stream of air along the wall sides of the passage way. Other such devices have been proposed such as grids connected to the exit end of the centrifugal blower housing.
While the disclosed proposals may function as intended, their efficiency is questionable when package space is somewhat smaller due to the ever increasing compactness of engine compartments. Therefore, it would be desirable to provide a compact centrifugal blower assembly which minimizes airflow separation between the blower and a heat exchanger downstream and which reduces or eliminates noise.
It is an object of the present invention to provide a centrifugal blower assembly for use in a heat exchange system which uses a non-linear, non-planar shaped diffuser disposed between the centrifugal blower housing and the heat exchanger which minimizes airflow separation therebetween.